Comparison of two rapid culture methods for detection of cytomegalovirus in clinical specimens

Comparison of α-glucosyl hesperidin of citrus fruits and epigallocatechin gallate of green tea on the Loss of Rotavirus Infectivity in Cell Culture

A number of secondary plant metabolites (e.g., flavonoids) possess antiviral/antimicrobial activity. Most flavonoids, however, are difficult to study, as they are immiscible in water-based systems. The relatively new semisynthetic α-glucosyl hesperitin (GH), and the natural plant product epigallocatechin gallate (EGCG) are unique among most flavonoids, as these flavonoids are highly soluble. The antiviral activity of these plant metabolites were investigated using the rotavirus as a model enteric virus system. Direct loss of virus structural integrity in cell-free suspension and titration of amplified RTV in host cell cultures was measured by a quantitative enzyme-linked immunosorbent assay (qEIA). After 30 min. 100 × 10(3) μg/ml GH reduced RTV antigen levels by ca. 90%. The same compound reduced infectivity (replication in cell culture) by a similar order of magnitude 3 to 4 days post inoculation. After 3 days in culture, EGCG concentrations of 80, 160, and 320 μg/ml reduced RTV infectivity titer levels to ca. 50, 20, and 15% of the control, respectively. Loss of RTV infectivity titers occurred following viral treatment by parallel testing of both GH and EGCG, with the latter, markedly more effective. Cytotoxicity testing showed no adverse effects by the phenolic concentrations used in this study. The unique chemical structure of each flavonoid rather than each phenolic's inherent solubility may be ascribed to those marked differences between each molecule's antiviral (anti-RTV) effects. The solubility of EGCG and GH obviated our need to use potentially confounding or obfuscating carrier molecules (e.g., methanol, ethanol, DMSO) denoting our use of a pure system environ. Our work further denotes the need to address the unique chemical nature of secondary plant metabolites before any broad generalizations in flavonoid (antiviral) activity may be proposed.

Analysis of human cytomegalovirus DNA in urines of newborns and infants by means of a new ultrarapid real-time PCR-system

BACKGROUND

Amplification techniques such as PCR are becoming increasingly popular in the field of diagnosis of human cytomegalovirus (HCMV) also, thus substituting conventional techniques like the time consuming HCMV antigen or cell culture assays. Current PCR protocols however, are labor intensive, and moreover, the need for extensive postamplification manipulations increases the risk of false positive results due to contamination with amplified products.

OBJECTIVES

to overcome these shortcomings, the new ultrarapid and semi-automated real-time LightCycler PCR-system (LC-PCR), which combines amplification and detection in a closed capillary system, was tested for its suitability in diagnosis of HCMV in urines.

STUDY DESIGN

73 urine samples from 64 newborns and infants suspected of having congenitally or postnatally acquired HCMV were tested with the LC-PCR and results were compared with those obtained in parallel with a conventional PCR-ELISA and the rapid shell vial assay for detection of HCMV early antigen (EA-assay).

RESULTS

with these methods, 31 newborns/infants were found to be infected with HCMV. HCMV DNA was detected in 39 urines while the EA-assay was positive in 33 urines. All the EA positive samples were also positive for HCMV DNA. In the urines of the remaining 33 newborns (34 urine samples) neither HCMV DNA nor EA were detectable. The overall agreement of the two PCR tests was 100% while a 92% agreement was obtained between the PCR and the EA-assays. As the sensitivity of the three tests turned out to be quite similiar, the discrepancy observed in the positive rate between PCR and EA-assay is due to other factors which will be discussed in detail. However, while LC-PCR takes only about 2 h from sample preparation to result generation, the EA-assay, such as the conventional PCR-ELISA, needs 24-48 h. Furthermore, due to its capability to perform cycle-by-cycle monitoring, the LC instrument enables semi-quantitative analysis of HCMV viral-load.

CONCLUSIONS

LC-PCR is a suitable new tool for routine analysis of HCMV in the urines of newborns and infants. Compared to the conventional PCR-ELISA a considerable increase in test rapidity and reliability is achieved without the need to sacrifice sensitivity.

Cadaveric skin allograft-associated cytomegalovirus transmission in a mouse model of thermal injury

As a routine procedure to provide temporary coverage for burn wounds, cadaveric skin allografts have been used in patients with massive thermal injuries. In this study, CMV infection associated with skin grafting was investigated. Graft-associated CMV transmission was shown in a mouse model of thermal injury. Skins from mice 100 days after a nonlethal dose of murine CMV (MCMV) infection contained MCMV DNA and mRNA, although the virus was not isolated from these murine skins. When these skins were grafted to burned mice, the marked growth of MCMV was demonstrated in salivary glands. No viral growth was shown in the salivary glands of unburned mice or CMV sero(+) mice after grafting with these skins. When severe combined immunodeficient beige (SCID-beige) mice were used as recipients for CMV sero(+) skins, all mice died within 30 days after the grafting. Only 1 PFU/mouse of MCMV was shown to be 1 LD(50) in SCID-beige mice, while a 50% mortality rate was shown in normal unburned mice infected with 5 x 10(5) PFU/mouse of MCMV. This indicates that a very small amount of CMV contained in skins is sufficient to induce CMV infection in immunocompromised hosts. On the other hand, human CMV (HCMV) DNA and mRNA were detected by PCR analysis in 55% (DNA) and 33% (mRNA) of cadaveric skins, although the isolation of HCMV from cadaveric skin homogenates was not achieved in tissue cultures. CMV sero(-) patients with severe burn injuries may have a high risk for CMV infection associated with allografts of cadaveric skins.

Aluminosilicates enhance the infectivity of cytomegalovirus in urine using centrifugation-enhanced antigen detection technology

Due to the inherent lability of CMV, necessary laboratory identification of this infectious agent is often compromised by a delay in specimen transport. Previous studies have addressed the phenomenon of infectivity enhancement/reduction in the rate of infectivity loss by the incorporation into various viral assay systems of trace concentrations of the adsorbents montmorillonite (bentonite [M]) or kaolinite (kaolin [K]). We extended these studies to the clinical setting to identify whether such aluminosilicates would effect an enhanced level of CMV infectivity. The shell vial assay-indirect immunofluorescent assay (SVA-IFA) was utilized in comparative testing throughout this study. The addition of trace concentrations of M or K to the SVA-IFA was found to enhance the infectivity of CMV in urine by 115 and 126%, respectively. The total CMV detection rate by SVA-IFA was 29% (30/105). Three of the 30 (10%) CMV positive specimens were detected only in shell vials which had been supplemented with K or M. Two specimens were isolation positive alone. The addition of K or M to shell vials immediately prior to the start of the SVA-IFA has the potential of (a), enhancing assay readability by increasing the number of fluorescent focus units per vial monolayer and (b), of detecting positive urine specimens with low viral titers which might otherwise not be identified using the conventional SVA-IFA procedure.

Comparison of monoclonal antibodies for immunostaining in the cytomegalovirus shell vial assay on 4,388 specimens

The shell vial assay is a sensitive, rapid test for the detection of cytomegalovirus (CMV) in a variety of specimens. The sensitivity of this assay is dependent on a number of factors including the antibodies used for immunostaining. Monoclonal antibodies to the CMV major immediate-early antigen (p72) from Chemicon (MAB810) and Dupont (NEA-9221) were assessed side by side in duplicate vials on 4,388 specimens from a patient population consisting of > 90% organ transplant recipients. A total of 240 specimens (5.5%) were CMV positive in either one or both vials. Positivity rates were variable across different specimen types but highest (12.9%) in urine specimens. Of the positive specimens, 175 (72.9%) tested positive in both vials, 43 (17.9%) tested positive in the Chemicon-stained vial only, and 22 (9.2%) tested positive in the Dupont-stained vial only (P < 0.01, McNemar's chi-square test). This gave an overall positivity rate of 5.0% for Chemicon antibodies and 4.5% for Dupont. There was no difference in the fluorescent focus counts produced by the two antibody sets. It is concluded that use of the Chemicon antibodies provides increased sensitivity of detection of CMV in the shell vial assay above that afforded by the Dupont antibody.

Effects of enhancing agents on detection of cytomegalovirus in clinical specimens

Dimethyl sulfoxide, dexamethasone, and calcium were tested in combination for their enhancing effects on cytomegalovirus detection in shell vial cultures on 1,579 clinical specimens obtained primarily from adult solid-organ transplant recipients. Fluorescent-focus counts were elevated for the cytomegalovirus-positive urine specimens (P < 0.01) and throat washings (P < 0.05) but not for the tissue biopsy or blood samples. Epidermal growth factor also increased focus counts but provided no additional benefit when used in combination with the other agents. The triple-combination treatment did not increase the number of positive specimens identified.

Detection of human cytomegalovirus in urine samples by cell culture, early antigen assay and polymerase chain reaction

With the advent of effective therapy rapid, sensitive and reliable assays for diagnosis of human cytomegalovirus (HCMV) infections are required. In a total of 1,928 urine samples, detection of HCMV-immediate early antigen in a spin amplified microplate culture by a monoclonal antibody and immunoperoxidase staining (EA-assay) was compared with virus isolation in cell culture. Sensitivity of the EA assay was 85.5% and specificity was 99.5% compared with virus isolation. Overall agreement of both assays was 97.8%. In addition, in 235/1,928 urine samples amplification of HCMV-DNA was performed by means of polymerase chain reaction (PCR) using primers from the immediate early (IE1) gene region and 141/1,928 using primers from the late region (LA). The sensitivity of PCR compared with virus isolation was 67.8% for IE1 primers and 94.1% for LA primers (statistical significance: p < 0.01, Chi-square-test). Overall agreement between virus isolation and PCR was 88.5% for IE1-PCR and 84.4% for LA-PCR. Discordant results were more often found in adults with acute infection and immunocompromised patients than in infants.

Physical and chemical methods for enhancing rapid detection of viruses and other agents

Viral replication events can be enhanced by physical, chemical, or heat treatment of cells. The centrifugation of cells can stimulate them to proliferate, reduce their generation times, and activate gene expression. Human endothelial cells can be activated to release cyclo-oxygenase metabolites after rocking for 5 min, and mechanical stress can stimulate endothelial cells to proliferate. Centrifugation of virus-infected cultures can increase cytopathic effects (CPE), enhance the number of infected cells, increase viral yields, and reduce viral detection times and may increase viral isolation rates. The rolling of virus-infected cells also has an effect similar to that of centrifugation. The continuous rolling of virus-infected cultures at < or = 2.0 rpm can enhance enterovirus, rhinovirus, reovirus, rotavirus, paramyxovirus, herpesvirus, and vaccinia virus CPE or yields or both. For some viruses, the continuous rolling of infected cell cultures at 96 rpm (1.9 x g) is superior to rolling at 2.0 rpm for viral replication or CPE production. In addition to centrifugation and rolling, the treatment of cells with chemicals or heat can also enhance viral yields or CPE. For example, the treatment of virus-infected cells with dimethyl sulfoxide can enhance viral transformation, increase plaque numbers and plaque size, increase the number of cells producing antigens, and increase viral yields. The infectivity of fowl plague virus is increased by 80-fold when 4% dimethyl sulfoxide is added to culture medium immediately after infection. The heat shocking of virus-infected cells also has been shown to have a stimulatory effect on the replication events of cytomegalovirus, Epstein-Barr virus, and human immunodeficiency virus. The effects of motion, chemicals, or heat treatments on viral replication are not well understood. These treatments apparently activate cells to make them more permissive to viral infection and viral replication. Perhaps heat shock proteins or stress proteins are a common factor for this enhancement phenomenon. The utility of these treatments alone or in combination with other methods for enhancing viral isolation and replication in a diagnostic setting needs further investigation.

Comparison of shell vial culture and the suspension-infection method for the rapid detection of herpes simplex viruses

Shell vial culture (SVC) and suspension-infection (SI) (simultaneous seeding of culture cells and inoculation of sample) were compared for the detection of herpes simplex virus (HSV) in clinical specimens. Conventional culture methods using mink lung cells or the Vero cell subline C1008 were also compared with each other and with SVC and SI. Additionally, SVC and SI were compared for quantitative determination of HSV infectivity. Compared with conventional culture with mink lung cells, culture with C1008 cells was 98% sensitive, and the sensitivities of SVC and SI were 94% and 93%, respectively. In quantitative determinations, titers of infectious HSV in positive clinical samples were a mean of five- to six-fold higher, as detected in SVC compared with SI titrations. For quantitative detection of infectious HSV, SVC was more sensitive than SI; however, for diagnosis of HSV in clinical specimens, no significant difference was observed between SI and SVC.

A rapid culture alternative to the shell-vial method for the detection of herpes simplex virus

The rapid test for detection of herpes simplex virus (HSV) in clinical specimens based on infection of cells in suspension (SI test) was compared to the shell-vial culture (SVC) method and conventional culture. Mink lung cells were used throughout the study. Detection of HSV was not significantly different whether using SI or SVC. The sensitivity of SI in detecting HSV, when compared with conventional culture, was 93.0% using 0.1 ml inocula and 98.3% using 0.5 ml inocula. The time to obtain a final result with both SI and SVC was 1 day compared with 1-7 days by conventional culture. The SI method detected both HSV type-1 and HSV type-2 clinical isolates. The SI technique is a simple method for the rapid detection of HSV and can yield diagnostic results with a minimum of technical manipulations.

Improved detection of cytomegalovirus viremia in AIDS patients using shell vial and indirect immunoperoxidase methodologies

One hundred twelve peripheral blood specimens were tested for the presence of cytomegalovirus (CMV) by the tube culture indirect immunoperoxidase (TC-IPA) procedure, the shell vial assay [shell vials were pre- and postinoculation treated with medium containing 2 of 10% fetal bovine serum (FBS) or 100 micrograms% cortisol] (SV-IFA), and conventional (MRC-5) tube cultures (TC-CPE). CMV was detected in 25 (22%) of the 112 specimens tested by at least one of these methods. The detection/isolation of CMV among the 25 positive specimens in shell vials maintained with 2% FBS, 100 micrograms% cortisol + 2% FBS, and 10% FBS was 36, 44, and 52%, respectively. Detection/isolation of the virus from blood by TC-IPA and TC-CPE was 52% and 76%, respectively. A significantly greater CMV detection rate occurred using TC-CPE compared to SV-IFA treated with medium supplemented with an FBS concentration of 2% (P = .0132), but not medium containing the higher serum supplement or the glucocorticoid (P greater than .05). Differences in the identification of a CMV viremia were observed by IPA, SV-IFA, and TC-CPE methodologies on a patient-to-patient basis, denoting the necessity of incorporating each methodology into the CMV screening panel. Demographic analysis of 82 AIDS patients showed a CMV viremia prevalence of 9% (2/28) in intravenous drug users, 57% (27/47) in homosexual patients, and 22% (2/9) in heterosexual and transfusion patients. Overnight (24 hr) storage of whole blood at 4 or 24 degrees C, respectively, reduced CMV recovery by 40% and 65%, when tested by TC-CPE.(ABSTRACT TRUNCATED AT 250 WORDS)

Suitability of infection of cells in suspension for detection of herpes simplex virus

Detection of herpes simplex virus in clinical specimens by the suspension-infection technique was compared with detection by conventional cell culture. The sensitivity and specificity of the suspension-infection technique compared with those of conventional culture were 95.9 to 98.2% and 97.5 to 100%, respectively, depending on the cell line used in the tests. The mean time to diagnosis by the suspension-infection technique was 1 day, compared with 4.8 days by conventional culture. Comparable detection of low-level positive specimens was observed with the methods. In a clinical setting, the isolation rates obtained by suspension-infection and conventional culture were indistinguishable. These results indicate that the suspension-infection method can be used for the detection of herpes simplex virus and can yield rapid diagnostic results without a time-consuming centrifugation step.

The value of immunohistochemistry and in situ hybridization in detecting cytomegalovirus in bone marrow transplant recipients

Autopsy tissues of 19 patients with complications after bone marrow transplantation (BMT) were analysed for the presence of cytomegalovirus (CMV) using histochemical methods. CMV antigens were detected by antibodies to CMV Immediate Early Antigen (IEA) or CMV Late Antigen (LA). CMV-DNA was detected by DNA in situ hybridization (DISH). IEA was detected in one or more tissues in 79% of 14 patients from whom frozen tissue was available. CMV-DNA was detected on paraffin sections in 84% of all 19 patients. CMV components were present in all organs studied; the highest incidence was found in lung, gastrointestinal tract and kidney. In histology, only 37% of patients showed signs of CMV infection by the presence of cytomegalic cells with nuclear inclusions (or so called "owl eye cells"). In tissue culture, only 33% of 15 patients were CMV positive. Serologically, 68% of all patients had active CMV infection, as indicated by a rise in antibody titres. We conclude that the quick detection of CMV IEA and CMV-DNA has a high sensitivity and predictive value, which is comparable to or exceeds the serological detection of CMV.

Enhanced recovery of cytomegalovirus in conventional tube cultures with a spin-amplified adsorption

Low-speed centrifugation-mediated adsorption was evaluated as an enhancement of infectivity of clinical and laboratory strains of cytomegalovirus (CMV) occurring with cells grown in conventional culture tubes. The time required for reporting of primary isolates of CMV from urine specimens adsorbed onto monolayers of WI-38 cells in culture tubes was calculated. Of 668 specimens adsorbed by the stationary phase (SP) method, 98 were positive by cytopathic effect (CPE) that required an average of 16.8 days for recovery in culture. However, the appearance of CPE required a shorter average time of 11.9 days for 70 CMV strains isolated from 283 specimens adsorbed in tube cultures by the spin-amplified (SA) method. In another phase of clinical CMV recovery, urine specimens were adsorbed by the SA method onto cell cultures grown in both shell vials and test tubes. Of 594 specimens inoculated, a total of 74 were positive by either CPE in test tubes or immunostaining-localized early antigen in shell vials. Approximately one-third of these CMV isolates were recovered only by CPE from specimens adsorbed by the SA method in test-tube cultures. In a related study to further evaluate differences between adsorption methods, the AD-169 laboratory strain of CMV was adsorbed by SP and SA methods onto MRC-5 cells grown in both culture vessels. Early antigen detection by immunomicroscopy was found in the infected cells at least 2 to 4 days prior to the appearance of CPE, regardless of adsorption procedure. In both vessels, the replication of AD-169 virus in cultures adsorbed by the SA method consistently exceeded that of virus adsorbed by the SP procedure. CPE occurred 24 to 48 h earlier and progressed two to four times more extensively; early antigen was expressed two- to fourfold greater within 24 to 48 h postinfection; and foci of infected cells containing late antigen were two to four times greater in number at 1, 2, and 5 days postinfection. Overall, the replication and enhancement of infectivity of laboratory and clinical strains of CMV as determined by CPE and early and late antigen expression occurred most efficiently with specimens adsorbed by the SA method onto cultures grown in conventional tubes or shell vials.

Comparison of monoclonal antibodies for rapid detection of cytomegalovirus in spin-amplified plate cultures

Cytomegalovirus (CMV) was detected in 56 of 275 specimens (20%); 50 of 56 (89%) were detected by conventional culture, and 37 (66%) were detected by rapid assay at 72 h with a commercial monoclonal antibody and a pooled monoclonal antibody. Although the two antibodies were equally sensitive at 72 h, the pooled antibody gave a brighter, more easily detected signal. Other viruses were isolated from 9 specimens (3.3%) by conventional culture. Use of rapid assays alone fails to detect slow-growing CMV and non-CMV viral pathogens.

Continuous high-speed rolling versus centrifugation for detection of herpes simplex virus

Specimens submitted for diagnosis of herpes simplex virus infections were inoculated into shell vials and conventional culture tubes. Inoculated culture tubes were incubated with rolling at 96 rpm. Immunoperoxidase (IP) staining and cytopathic effects (CPE) were used to detect positive cultures. At 24 h, 42 (53%) of the rolled cultures were positive for CPE, while only 16 (21%) of the shell vials were CPE positive (P less than 0.01). No difference in sensitivity was seen between rolled and shell vial cultures that were inoculated with high-titered viral preparations and IP stained at 16 h. However, when low-titered preparations were used, 39 of 41 (95%) were IP positive by the high-speed roller method at 64 h postinoculation, while only 24 of 41 (58%) were IP positive with shell vials (P less than 0.01). These results indicate that high-speed roller method at 64 h postinoculation, while only 24 of 41 (58%) were IP positive with shell vials (P less than 0.01). These results indicate that high-speed rolling is better than the shell vial technique for the detection of herpes simplex virus by IP staining.

Cytomegalovirus retinitis

Cytomegalovirus retinitis is a frequent and serious complication of various conditions, including diseases characterized by impaired immunity, such as the acquired immunodeficiency syndrome. Due to recent advances in the treatment of cytomegalovirus retinitis, accurate diagnosis and management have become increasingly important. In this review, the authors present the epidemiology, clinical features, diagnostic testing, treatment with complications, and prognosis of cytomegalovirus retinitis. A differential diagnosis is presented and the characteristic ocular lesions are illustrated.

Multisite evaluation of a monoclonal antibody reagent (Syva) for rapid diagnosis of cytomegalovirus in the shell vial assay

A pre-cytopathic effect (CPE) monoclonal antibody reagent (Syva Co., Palo Alto, Calif.) was evaluated in four laboratories for the rapid detection of cytomegalovirus (CMV) in shell vial cell cultures at 16 to 24 h and 40 to 48 h postinoculation. Results were compared with those obtained by inoculation of the specimen into conventional tube cell cultures that were examined for the presence of typical CMV CPE and subsequently tested by reaction with the monoclonal antibody reagent in an indirect immunofluorescence test. Of 937 specimens, CMV was positive in 184 (20%). CMV was detected twice as frequently in shell vials only (n = 29) as in conventional tube cell cultures (n = 14). Pre-CPE shell vial assay was 91% sensitive (range, 84 to 98%) and 96% specific (range, 93 to 98%) compared with the detection of CPE in conventional tube cell cultures. Overall, 137 of 166 (83%) and 143 of 166 (86%) of the CMV strains were detected at 16 to 24 h and 40 to 48 h postinoculation, respectively. The Syva reagent produced sensitive and specific results for the rapid detection of CMV infection in shell vial cell cultures and reliably confirmed the presence of the virus as detected by CPE in conventional tube cell cultures.

Diagnosis of cytomegalovirus infection by detection of the early antigen of cytomegalovirus in cell cultures

Conventional virus isolation and detection of cytomegalovirus (CMV) early antigen by immunofluorescence staining of cultured cells were compared in the diagnosis of CMV infection from urine specimens. By virus isolation, 33 specimens out of 333 studied were positive, and the mean length of culturing time for a positive result was 23 days (range from 6 to 45 days). By early antigen detection, 35 specimens were positive after 20 hours in culture, but the number of positive findings increased to as high as 49 after 7 days in culture. It is recommended that, in addition to the early antigen staining after one day in culture, cells should also be stained after one week in culture, because the sensitivity is essentially improved by extended culturing time.

Modified spin-amplified adsorption procedure with conventional tissue culture tubes for rapid detection and increased recovery of herpes simplex virus from clinical specimens

Conventional culture tubes were used in a modification of the spin-amplified adsorption procedure for recovery of herpes simplex virus (HSV) from clinical specimens. The sensitivity of isolation of HSV from 864 specimens adsorbed by the spin-amplified method was 100% (127 of 127), compared with 88.2% (112 of 127) for stationary-phase-adsorbed specimens. Cytopathic effect developed more rapidly in 32.1% (36 of 112) of isolates adsorbed by spin amplification than in those adsorbed by stationary means. In a separate quantitative study, cultures of HSV type 1 adsorbed by spin amplification yielded higher antigen levels and greater cytopathic effect than stationary-phase-adsorbed cultures. Cells grown in conventional tissue culture tubes may be used in a spin-amplified adsorption for rapid detection and increased sensitivity of HSV isolation.